1. Field of the Invention
This invention relates to a pattern drawing apparatus for drawing a desired pattern on an object by using charged beams, such as electron beams, ion beams, or the like, and more particularly to a charged beam pattern drawing apparatus with a pattern re-size function.
2. Description of the Related Art
In recent days, various types of electron beam pattern drawing apparatuses have been developed and used for drawing desired patterns on the object such as semiconductor wafers and masks. In this type of pattern drawing apparatus, the data of a pattern of IC as prepared by CAD (computer aided design) technique, such as LSI, is converted into bit data, which is used in the pattern drawing by electron beams. By the bit data, the on and off of the beam are appropriately controlled, to form a desired pattern on the object.
In the development of LSI, the thickness of a pattern is frequently changed in order to make a fine adjustment of the electric characteristic thereof. This pattern thickness change is called a "re-size". In the conventional re-size technique, it is often required to re-design the pattern to change its thickness by the CAD, or to modify the drawing data provided for the drawing apparatus by using a conversion software. This re-size work is time consuming and troublesome, hindering the development of the LSI.
In modifying the CAD data for re-size processing, it is necessary to give instructions, which change the sizes of a number of LSI patterns. In this case, the converted data must be further processed so as to convert the data format used in the pattern drawing apparatus. The execution of the conversion program used for re-sizing the drawing data of the pattern drawing apparatus takes longer to accomplish, if the drawing data is complicated. Generally, LSI includes a combination of patterns consisting of 10 to 20 stacked layers. The above re-sizing process must be applied to all these patterns. Thus, the conventional re-sizing process requires allot of time and effort, even when the degree of re-size of the LSI pattern is small.
As described above, employing the conventional re-size technique requires allot of time and effort, thereby making the re-size processing quite difficult. The same problem not only exists in the electron beam pattern drawing apparatus, but also in a charged beam such as the ion beam pattern drawing apparatus.